Autumn drainage checklist: stopping leaf-fall blockages before they start

Autumn causes more drainage call-outs than any other season. Leaf fall, heavy rain and the first cold snaps combine to overwhelm gullies and soakaways that coped fine all summer. An hour of checks now usually saves an emergency call-out in November.

Why autumn is the worst season for drainage

Leaves, silt and grit wash off roofs, roads and car parks straight into gully pots. Once a gully pot silts up, surface water has nowhere to go and starts ponding — which is when driveways flood, car parks pool and water finds its way into thresholds and basements. On older systems, the same debris travels into the pipework and settles at bends, gradually reducing the bore until the run blocks completely.

The checklist

1. Clear gutters and downpipes first

There is no point clearing a gully if the gutter above it is still shedding leaves into it. Clear gutters, check the downpipe shoe discharges cleanly into the gully, and fit leaf guards where trees overhang.

2. Lift and empty every gully pot

A gully pot is designed to trap silt below the outlet. Scoop it out, flush with a hose and check the water drains away briskly. Slow drainage after cleaning means the blockage is downstream, in the pipe run, not in the pot.

3. Check inspection chambers and manholes

Lift the covers on your inspection chambers. You want to see clear, flowing water in the channel and clean benching. Standing water, silt build-up or a smell of stale effluent means a partial blockage that will fail once rainfall increases.

4. Test soakaways and surface water outfalls

Run a hose into the system for a few minutes. A healthy soakaway will absorb the water steadily. If it backs up, it is either silted or saturated — both need investigating before winter rainfall arrives.

5. Book planned jetting on high-risk sites

Sites with mature trees, food outlets, workshops or large car parks benefit from a planned autumn jet and gully clean. It is a fraction of the cost of an out-of-hours emergency during a storm.

Warning signs that need action now

• Water ponding on a driveway, yard or car park after light rain
• Gurgling from sinks, toilets or external gullies
• Slow-emptying toilets or baths, especially on ground floor fixtures
• Smells around manhole covers or gullies
• Damp patches or staining appearing at the base of external walls

Commercial sites: what to add to the checklist

• Interceptor and separator chambers checked and emptied before the wet season
• Car park channel drains and slot drains cleared of silt and grit
• Pump station wet wells inspected and float switches tested
• Drainage plans updated after any recent groundworks
• A CCTV survey on any run that has blocked more than once in the past year